X-ray apparatus



April 12, 1938. A. BOUWERS X-RAY APPARATUS Filed Dec. 21, 1933 fm e/rfor Patented Apr. 12, 1938 UNITED STATES PATENT OFFICE X-RAY APPARATUS aDutch company Application December 21, 1933, Serial No. 703,461 InGermany December 27, 1932 16 Claims.

My invention relates to X-ray apparatus and similar devices.

While I shall describe my invention in connection with X-ray devices, itis not limited thereto but is also applicable to other electric devicesin which a load is supplied from a transformer, for example devicesusing discharge tubes for illuminating purposes.

X-ray devices are known in which an X-ray tube is integral with ahigh-tension supply transformer, however, due to the comparatively largecircumference of the transformer, such devices have a comparativelylarge size and are not adapted to be readily moved. To reduce the sizeof such devices, and to allow the X-ray tube to be brought close to thetransformer, it has been proposed to immerse the X-ray tube andtransformer in oil. Such oil-immersed devices have, however, thedisadvantage that the same: oil which absorbs the heat developed in theX-ray tube, which is very low relative to the heat losses of thetransformer, is also in contact with the transformer.

The present invention relates to an X-ray device which has smallerdimensions than those of prior constructions. According to the inventionthe high-tension transformer of the X-ray device is preferably formed asa radial transformer (i. e. a transformer in which the magnetic coremate rial is distributed about the periphery of the coils) and comprisesa column which is divided in half in the direction of the length, orwhich is axially bored, and in which the X-ray tube is housed. In thiscase, the circumference of the device is altered not at all or only to aslight extent by the load.

In one embodiment of my invention I form the core of the transformer ofbuckle-shaped sheets or laminations radially arranged to surround a loadwhich is supplied from this transformer. These sheets may be united in amanner known per se into a number of bundles, in which case thetransformer is preferably surrounded by a corrugated sheath, whosecorrugations extend in i the direction of the length of the bundles andcngage'th'e edges thereof to support same.

When applying my invention to an X-ray device I prefer to use acylindrical X-ray tube which is symmetrically surrounded by thetransformer, and when the length of the X-ray tube is greater than thatof the transformer, tube-ends of substantially equal length protrudefrom either side of the transformer. These tube-ends are preferablysurrounded, with some intermediate space, by metal ormetalizedprotective hoods which may also serve for the attachment of an electricfan for cooling the transformer and X-ray tube.

The magnetic core of the transformer may be provided with a longitudinalslot for the passage of the X-rays. This. slot is preferably also usedfor passing the current conductors, in an insulated manner through themagnetic body, from the high-tension coil to the tube-ends at the twoend surfaces of the transformer. In order that the usual re-entrantsparts of the X-ray tube may be capable of withstanding a considerableportion of the potential difference existing between the electrodecarried thereby and the transformer core, the current conductors whichpass through the re-entrant parts are supported by centrallyboredinsulating stoppers or bushings mounted in the re-entrant parts.

The transformer windings which radially surround the X-ray tube aredisposed within the annular window of the magnetic core, and areseparated from the X-ray tube by the inner parts of the laminations.Thus, the space is utilized more efficiently than, for example, with awell-known form of construction of an X-ray device in which a neck ofthe X-ray tube extends into a window of the transformer.

T economize on the insulation between the X-ray tube and the surroundingmetal, an X-ray tube is used in which the part of the tube Wall oppositethe transformer body is entirely of metal,

or is provided with a metal layer. If the length of the metal middleportion of the X-ray tube is less than that of the hollow portion of thetransformer core in which the tube is arranged, the metal portion shouldbe extended on either side by means of metal layers, such as coatings oftinfoil on the outside of the tube wall, at least as far as the sides ofthe transformerv Preferably, the transformer sheets, the narrow side ofwhich is adjacent the tube, are sloped or rounded at Fig. 3 is a topview of another embodiment of the invention comprising a shelltransformer;

Fig. 4 is a partly sectionized side view of the device shown in Fig. 3;

Fig. 5 is a top view of a device according to the invention comprising acore-type transformer;

Fig. 6 is a side view of the device shown in Fig. 5.

The device shown in Figures 1 and 2 comprises a, cylindrical transformerhaving an iron core built up of buckle-shaped sheets or laminations l.The sheets I are grouped together in lots of, for instance to 10, intobundles 2, which are surrounded by a corrugated iron sheath 3, forinstance of tin plate. As is shown in Fig. 2, the corrugations of sheath3 extend in the direction of the length of the transformer, and theouter ends of the bundles fit into the corrugations so that the relativespacing of the bundles remains unvaried.

symmetrically arranged Within the central cavity formed by thetransformer core is an X-ray tube having a Wall comprising a metalmiddle portion 4 to the ends of which are sealed glass members 5 and 6having re-entrant portions [3 and I4 carrying an anode l and a cathode 8respectively.

The portions of glass members 5 and 6 opposite the transformer arecoated with a satisfactorily-adhering lay-er of tinfoil 40 extending tothe dotted lines 9 and H], which reduces the danger of flash-overs andof deterioration of the glass members. This is probably due to the factthat the quantities of air which are unavoidably entrapped between thetube wall and the transformer core are electrostatically protected bythe metal coatings so that no ionization can occur therein.

The portions of the tube protruding from the interior of the transformerare surrounded by metal hoods II and I2. If the power of the device issufiicient to render cooling of the X-ray tube and the transformerdesirable, an electric fan (not shown) may be attached to one of thehoods, preferably to hood ll adjacent the anode.

Although the insulating length of the glass members 5 and 6 ismaterially reduced by the metal coatings, this is not necessarily adisadvantage. It is, however, preferable that the reentrant portions 13and I4 withstand a substan tial part of the potential drop. To renderthis possible the re-entrant portions have arranged in themcentrally-bored stoppers or bushings l5 and N3 of insulating material,which bushings also support the current conductors l1 and 18, which passfrom the transformer to the electrodes of the tube and which aresurrounded by good insulating material.

To allow the X-rays to pass through the transformer core withoutinterference, a longitudinal slot l9 having the width of the cone ofX-rays (see Fig. 2) is provided in the core and which, owing to itswedge shape, conforms closely to the cone of the X-rays. The slot I9also allows the passage of the current conductors l1 and I8 through thetransformer core. As the entire remaining part of the circumference ofthe coils can be provided with the transformer iron, a great saving inspace is obtained.

Windings 20, 2|, and 22, which have the form of concentric. cylindricalcoils, are located in the annular window formed within the transformercore. The primary windings 20 are surrounded by the secondary windings2| and 22 and are insulated from these windings by low-tensioninsulation (not shown). The secondary windings 2| and 22 are adjacentlydisposed and are spaced apart in the direction of their width to providea space through which the X-rays may pass. The secondary windings 2| and22 have their inner ends interconnected at 4|, and are so wound that thevoltages induced in them are additive. Thus, when the X-ray tube is inuse, the innermost layers of windings 2| and 22 will have substantiallythe same potential as the core, in which case the interconnection 4| ofthe secondary windings, together with the iron body, can be grounded.The high tension ends of the secondary windings are located on the outerside and a cylinder 23 of insulating material prevents the occurrence offlashing-over between the outermost layers of windings and thetransformer core.

To avoid fiashing-over between the parts of the secondary windings whichhave the total voltage relative to each other, the ends of windings 2|and 22 are tapered, i. e., the layers of the windings are made narrowertowards the outside. Consequently, flashing-over to the transformer corein the length direction cannot occur so easily. As the windings haveonly half the voltage relative to the transformer core, it is entirelyin agreement with the load conditions that the increase of the distancefrom the transformer core to the end of the adjacent secondary windingis only half as great as the increase of the distance between adjacentends of the secondary windings. The trapezoidal form of these windingshas 'the further advantages that this shape, as well as the shape of theslot 19 of the iron core, corresponds to the form of the X-ray beamemerging from a window 24.

The device may be supported by a bail 25 provided with trunnions 2B and21 engaging apertures of the metal hoods H and 12.

As shown in Figure 1, the transformersheets have rounded corners,whereby at the point at which the electrostatic load of the tube wallcommences, the electric field at the corner of the sheets is weakenedand the tube wall is thus loaded to a lower degree.

It is possible, in the above-described manner to make a complete X-raydevice for powers which are not excessive, for example X-ray .devicesfor use in dentistry. A device of this type has been made having alength of about 20 cms. and a diameter not exceeding 12 cms. Devices ofsuch construction may also be used for larger powers, for example fordiagnostical purposes. In the latter case the provision of a fan and aslightly greater copper section of the transformer windings may lead tothe desired increase of the loading capacity. The form of thetransformer is particularly eifective in view of the possibility ofcooling.

Although it has been proposed to surround; an Xray tube by thetransformer windings and, if desired, to arrange the magnetic corewithin the tube, the device according to the invention offers, incomparison with such construction, the advantage of using a transformerhaving a closed core.

If it is desired to unite the X-ray tube with a shell transformer of theusual form, this may be effected in the manner diagrammatically shown inFigs. 3 and 4. In this case, the transformer column is divided in thedirection of the length, the sheets of the bundles 28 and 29 beingarranged as the leaves of a bound book so as to-torm a recess bearingagainst the cylindrical X-ray tube 30. Also in this construction anexcessive concentration of the lines of force of theelectric field onthe corners of the transformer core is avoided by sloping the corners.

Even a core transformer may beunited with the tube in accordance withthe principles of the invention, for example, in the manner shown inFigs. and 6. As shown in these figures, an X- ray tube 32 is surroundedby the transformer coils 3| and is housed in the column 33 of thetransformer, which column is divided into two parts in the direction ofthe length (see Fig. 5). The magnetic circuit is closed through the yoke34 to surround the transformer coils.

The form of construction described with reference to Figs. 1 and. 2 is,however, preferable to the other example of construction on account ofthe very efficient use of the space occupied.

As has been stated, my invention is not limited to X-ray devices, butmay be used in other electric devices in which a load is supplied by atrans former and in which a compact structure is desirable.

While I have described my invention in connection with specific examplesand in specific applications, I do not wish to be limited thereto, butdesire the appended claims to be construed as broadly as permissible inview of the prior art.

What I claim is:

1. An X-ray device comprising an X-ray tube having a cylindricalenvelope and adapted to emit X-rays through a central portion thereof, ahigh-tension supply transformer for said X-ray tube having windings anda magnetic core having portions forming an elongated space, said X-raytube being mounted within said space concentrically and symmetricallywith respect to said portions and with its ends extending beyond theends of said transformer, each turn of said windings encircling saidcore portions and said X-ray time, said windings and core portionsforming a radially-extending space for the exit of the X- rays, andelectric supply leads connecting the ends of said tube to said windings.

2. A shock-proof X-ray device comprising a high-tension radialshell-type transformer having windings and a magnetic core havingportions forming an elongated space, an X-ray tube disposed within saidspace with its ends projecting from the sides of the transformer andcomprising an envelope having a conductive outer surface extending thelength of said core portions and disposed adjacent thereto, a protectivehousing having a substantially closed surface of conductive materialenclosing said tube and transformer and comprising two hoods eachsurrounding one end of said X-ray tube, said housing being electricallyconnected to the core of said transformer, and electric leads withinsaid hoods and connecting said X-ray tube and transformer.

3. An X-ray device comprising an X-ray tube adapted to emit X-raysradially through a central portion thereof, and having a cylindricalenvelope provided at its central portion with a conductive surface, ahigh-tension supply transformer for said X-ray tube having windings anda magnetic core having portions forming an elongated space, said X-raytube being mounted within said space concentrically and symmetricallywith respect to said portions and with its ends extending beyond theends of said transformer and with said conductive surface extending thewidth of said portions, each turn of said windings encircling said coreportions and said X-ray tube, said windings and core portions forming aradially-extending space for the exit of the X-rays, and electric supplyleads connecting the ends of said tube to said windings.

4. An electric device comprising an elongated electric discharge tubeand a high-tension supply transformer therefor, said transformer havinga magnetic core and windings, said core having a leg enclosed by saidwindings and branching in two branches which are spaced apart to form alongitudinal intermediate space, said tube being longitudinally disposedin said space, and supply leads connecting the tube to said transformer,said leads extending from each end of the tube to the adjacent end ofsaid windings.

5. An X-ray apparatus comprising an X-ray tube and a high-tension supplytransformer therefor, said transformer having a primary winding, asecondary winding and a magnetic core, said core being composed ofsubstantially rectangularly-shaped and rectangularly-aperturedlaminations arranged in radial symmetry, said windings being disposed inthe toroidal space formed by said apertures, and said tube beingdisposed in the central cylindrical space formed by said laminations,and electric supply leads connecting the ends of the two secondarywindings to said X-ray tube.

6. An X-ray apparatus comprising an X-ray tube having an envelope andelectrodes therein, a high-tension radial-type transformer having amagnetic core and windings, and supply leads for said X-ray tubeconnected to the high voltage ends of said windings, said core forming atoroidal space in which said windings are located and forming a centralcylindrical space in which said tube is symmetrically mounted, thecentral portion of said envelope adjacent to the core being providedwith a metallic surface.

7. An X-ray apparatus comprising an X-ray tube and a high-tensionradial-type supply transformer therefor having a magnetic core andcoils, said core forming a toroidal space having a casing of insulatingmaterial located therein and forming a central cylindrical bore havingthe X- ray tube disposed therein, said casing enclosing said transformercoils and having apertures in its ends, tubes of insulating materialfitting in said apertures, and electric supply leads connecting the highvoltage ends of the coils to the ends of the X-ray tube and passingthrough said insulating tubes.

8. An X-ray apparatus comprising an. X-ray tube having an envelope andelectrodes therein, a high-tension radial-type supply transformer forsaid tube having a magnetic core and windings, said core forming atoroidal space in which said windings are located and forming a centralcylindrical space in which said tube is symmetrically mounted, electricsupply leads for said X- ray tube connected to the output ends of saidtransformer, and a conductive member covering portions of the tubeenvelope adjacent to the core to prevent the setting up of an electricfield between the core and the adjacent envelope portions.

9. An X-ray apparatus comprising an X-ray tube having electrodes, anenvelope consisting of a central metal portion and glass portions sealedto the ends of said metal portion, a high-tension radial-type supplytransformer having windings and a magnetic core, and supply leads forsaid X-ray tube connected to the high voltage ends of said windings,said core forming a toroidal space in which said windings are locatedand forming a central cylindrical space in which said tube issymmetrically mounted, and a metallic coating in electrical contact withsaid metal portion and covering said glass portions throughout thelength of the transformer core beyond said metal portion.

10. An X-ray apparatus comprising an X-ray tube and a high-tensionsupply transformer having windings and a magnetic core, and output leadsconnecting the high. voltage ends of said windings to the ends of saidX-ray tube, said core consisting of radially-arranged rectangular O-shaped laminations, said laminations forming a toroidal space in whichsaid windings are located and forming a central cylindrical space inwhich said tube is mounted, the corners of the lamination edges adjacentto the X-ray tube being rounded.

11. An X-ray apparatus comprising an X-ray tube and a high-tensionsupply transformer therefor, said transformer comprising a magnetic coreand windings, said core being provided with a toroidal space in whichare located the windings of the transformer, and having a centralcylindrical aperture in which is symmetrically located the X-ray tube,and a'longitudinal slot in said core, said windings being divided in twoparts spaced from each other at the equatorial plane of the transformer,said slot and. the coil interspace together forming a lateral passagewayfor the X-rays emitted by said tube, and hightension insulated supplycables connecting said windings to the adjacent ends of the tube andextending into said slot.

12. An 'X-ray apparatus comprising an X-ray tube having an envelope andgenerating a laterally-emerging X-ray beam, and a high-tensionradial-type transformer for said tube, said transformer having amagnetic core, a primary winding, and a secondary winding, said coreforming a toroidal space in which said windings are 10- n cated andforming a central cylindrical space in which said X-ray tube issymmetrically disposed, said secondary winding comprising two coilsspaced apart to form about the equatorial plane of the transformer aspace, said X-ray beam passing through said space, said space increasingtoward the periphery to correspond to the increasing width of the X-raybeam, and electric supply leads connecting the high voltage ends of saidsecondary coils to said X-ray tube.

13. An X-ray installation comprisingan X-ray tube having-an envelope andelectrodes therein, said envelope having re-entrant portions ofinsulated material carryingsaid electrodes, a hightension supplytransformer for said tube having a magnetic core, said core beingprovided with a central duct in which said tube is disposed, the ends ofsaid tube extending beyond said core, a centrally-bored insulatedstopper in each reentrant portion, insulating tubes inserted in saidstoppers and supported thereby, said insulating tubes extendingoutwardly toward the transformer, and current supply leads connectingthe electrodes to the transformer, said leads being enclosed in saidinsulating tubes.

14. An X-ray apparatus comprising-an X-ray tube and a high-tensionsupply transformer therefor having primary and secondary windings,saidtransformer' having a core provided with a toroidal space in whichsaid windings are located,

said core having a central cylindrical spacein which saidtube islocated, each of said windings consistingof two coils spaced apartsymmetrically with respect to the equatorial plane of the trans former,a conductor having substantially the same potential as the magnetic coreand connecting the coil parts in series with each other, the coils ofthe secondary windings being wound in concentric layers with theinterconnected ends lying at the inner side and the other ends at theouter side, electric leads connecting said latter ends to the X-raytube, and a space between the outer layers of the secondary winding andthe core, which is at least partly filled with insulating compound.

15. An X-ray apparatus comprising an X-ray tube and a high-tensiontransformer having windings and a magnetic core, said core beingprovided with a toroidal space in which said windings are disposed andforming a central cylindrical-space in which said tube is symmetricallymounted, said-transformer windings consisting of a primary winding andof a two-coil secondary "winding, the coils of said secondary windinghaving a substantially trapezoidal sec-- tion with the longer parallelside turned toward the axis of the transformer, aconductorinterconnecting the inner ends of saidsecondary coils toform a seriesconnection, high-tension insulated conductors connecting the other endsof the secondary coils to the X-ray tube, and an insulating layer aroundthe outer surface and the ends of the coils.

16.An X-ra'y apparatus comprising an X-ray' tube having electrodes and alaterally emerging X-ray beam, said tube having an envelope comprisingacentral metal portion and glass portions sealed to the ends of saidmetal portion and carrying said electrodes, a window in said metalportion for the exit of the X-ray beam, a radialtype transformer havingprimary windings, secondary windings, and a magnetic core, said corehaving laminations forming a hollow spacein which said windings arelocated and forming a central cylindrical bore in which said tube isdisposed with the tube-ends protruding therefrom; said primary windingsbeing adapted to be electrically connected to the ordinary supplynetwork, said secondary windings having a midtap electrically connectedto said core and to said

